FeNO may help diagnose cough variant asthma

HOUSTON — Forced exhaled nitric oxide, or FeNO, may be useful for diagnosing cough variant asthma in patients with chronic cough who have normal spirometry, researchers reported at the American College of Allergy, Asthma and Immunology Annual Meeting.

“We know that cough variant asthma is a type of asthma in which the main symptom is a dry, nonproductive chronic cough in the absence of wheezing or shortness of breath. The condition is frequently underdiagnosed since baseline spirometric volumes are usually normal,” Talal M. Nsouli, MD, FACAAI, FAAAAI, director and founder of the International Cough Institute, professor of pediatrics and allergy/immunology at Georgetown University Hospital School of Medicine and director of the Watergate and Burke Allergy and Asthma Research Centers in Washington, D.C., said during a presentation. “We also know that airway inhibition is the basis of cough variant asthma and that FeNO is often used for patient evaluation, but that is still open to debate.”

For their study, Nsouli and colleagues sought to explore the value of FeNO measurements in diagnosing patients with chronic cough suspected for cough variant asthma. They enrolled 32 patients (mean age, 42.5 years) with lasting longer than 8 weeks, normal spirometry and abnormal Asthma Control Test (ACT) scores as well as nine control patients (mean age, 47 years) with normal spirometry and normal ACT scores. Both groups were skin test positive to environmental allergens, had normal chest X-rays and normal eosinophil counts.

Forced exhaled nitric oxide, or FeNO, may be useful for diagnosing cough variant asthma in patients with chronic cough who have normal spirometry, researchers reported at the American College of Asthma, Allergy and Immunology Annual Meeting.

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Of the patients with chronic cough, 91% had elevated FeNO measurements with mean average values of 64.4 ppb vs. the optimal normal cutoff value of 25 ppb and 60% had abnormal ACT scores of 15.4, according to the results. In contrast, control patients had normal FeNO measurements with mean average values of 16 ppb and normal ACT scores.

“Our study results suggest that FeNO may be useful for diagnosis of type 2-driven suspected cough variant asthma and may not only offer a helpful algorithm to unravel the clinical conundrum of chronic cough but also may lead to a reduction in misdiagnosis and health care costs,” Nsouli said. – by Melissa Foster

Reference:

Nsouli T. A202. Presented at: American College of Allergy, Asthma and Immunology Annual Meeting; Nov. 7-11, 2019; Houston.

Disclosure: Nsouli reports he is a consultant, speaker and advisory board member for AstraZeneca and Merck.